31013221 has 2 divisors, whose sum is σ = 31013222. Its totient is φ = 31013220.

The previous prime is 31013167. The next prime is 31013233. The reversal of 31013221 is 12231013.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 30636225 + 376996 = 5535^2 + 614^2 .

It is a cyclic number.

It is not a de Polignac number, because 31013221 - 2¹⁹ = 30488933 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31013251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15506610 + 15506611.

It is an arithmetic number, because the mean of its divisors is an integer number (15506611).

Almost surely, 2^31013221 is an apocalyptic number.

It is an amenable number.

31013221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31013221 is an equidigital number, since it uses as much as digits as its factorization.

31013221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 31013221 is about 5568.9515171170. The cubic root of 31013221 is about 314.1827171647.

Adding to 31013221 its reverse (12231013), we get a palindrome (43244234).

It can be divided in two parts, 310 and 13221, that added together give a palindrome (13531).

The spelling of 31013221 in words is "thirty-one million, thirteen thousand, two hundred twenty-one".